Last names starting with "O"
- Class of 1975 James O'Callaghan
- Class of 1968 Daniel O'Neill
- Class of 1961 John OBrien
- Class of 1979 Robert Oconner
- Class of 1952 John Oconnor
- Class of 1982 Neil Oconnor
- Angel Ohalloran
- Class of 1967 William Olivari
- Class of 2006 Isaac Olson
- Class of 1963 Vince Omalley
- Class of 1963 Vincent Omalley
- Class of 1983 Michael Orlando
- Class of 1981 Jesus Oropeza
- Class of 1985 Eric Ortega
- Frank Ortiz
- Class of 1955 Paul Osborne
- Class of 1959 William Oshea
- Class of 1995 Chris Oshida
- Emilio Osorio
- Class of 1968 Michael Osullivan
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About the Archbishop Riordan High School Alumni Directory
If you attended Archbishop Riordan High and want to be added to the alumni directory register now to add your name to the alumni list. You can share memories of those activities that you were involved with at Archbishop Riordan HS and you can view other alumni and read what other former students have posted about the time they spent at Archbishop Riordan.